Motor imagery vividness and symptom severity in Parkinson's disease

Motor imagery (MI), the mental simulation of movement in the absence of overt motor output, has demonstrated potential as a technique to support rehabilitation of movement in neurological conditions such as Parkinson's disease (PD). Existing evidence suggests that MI is largely preserved in PD, but previous studies have typically examined global measures of MI and have not considered the potential impact of individual differences in symptom presentation on MI. The present study investigated the influence of severity of overall motor symptoms, bradykinesia and tremor on MI vividness scores in 44 individuals with mild to moderate idiopathic PD. Linear mixed effects modelling revealed that imagery modality and the severity of left side bradykinesia significantly influenced MI vividness ratings. Consistent with previous findings, participants rated visual motor imagery (VMI) to be more vivid than kinesthetic motor imagery (KMI). Greater severity of left side bradykinesia (but not right side bradykinesia) predicted increased vividness of KMI, while tremor severity and overall motor symptom severity did not predict vividness of MI. The specificity of the effect of bradykinesia to the left side may reflect greater premorbid vividness for the dominant (right) side or increased attention to more effortful movements on the left side of the body resulting in more vivid motor imagery.     

Perceived unpleasantness and facial reactions to auditory stimuli

This study examined whether facial electromyographic (EMG) reactions differentiate between identical tone stimuli which subjects perceive as differently unpleasant. Subjects were repeatedly exposed to a 1000 Hz 75 dB tone stimulus while their facial EMG from the corrugator and zygomatic muscle regions were measured. Skin conductance and heart rate responses were also measured. The subjects rated the unpleasantness of the stimulus and based on these ratings they were divided into two groups, High and Low in perceived unpleasantness. As predicted the facial EMG activity reflected the perceived unpleasantness. That is, the High group but not the Low group reacted with an increased corrugator response. The autonomic data, on the other hand, did not differ between groups. The results are consistent with the proposition that the facial muscles function as a readout system for emotional reactions and that facial muscle activity is intimately related to the experiential level of the emotional response system.     

“Weapons effect” revisited: Motor effects of the reception of aversive stimulation and exposure to pictures of firearms

The effect of presenting images of firearms on the speed of clenching of the fist of human subjects simultaneously receiving an aversive stimulation was studied. It was thought that, whereas the classic interpersonal experimental situation confounds the effects of the stimulus presented and several interpersonal processes, speed of fist clenching in a noninterpersonal setting could constitute a valid measure of the subject's readiness to fight. Twenty-four male and 24 female students (ages > 20 and <36 years) were instructed to press with their right hand a device commanding the projection of slides upon reception of an acoustic signal. Speed of clenching of the hand was recorded in the four conditions generated by the combination of two levels of acoustic signal (aversive and nonaversive) and two modalities of slides (firearms or tools). The results show that the reception of aversive sound accelerates fist clenching. Simultaneous presentation of slides of firearms and reception of aversive noise increases the speed of clenching of the fist. The slides' main effect was not significant. More irritable subjects tend to execute this movement faster than their less irritable counterparts, and more emotionally susceptible subjects tend to be slower than less susceptible ones. Male subjects were faster than females. This pattern of results is discussed in relation to the hypothesis formulated by the authors.     

Inhibiting reactions to emotional versus non‐emotional response cues in schizophrenia: Insights from a motor‐process paradigm

Recent models of schizophrenia suggest deficient use of contextual response cues when confronted with countermanding emotional cues. It is important to clinically validate these models by testing patients diagnosed with schizophrenia on tasks with competing emotional and contextual response determinants. Control and schizophrenia groups completed a novel task that elicited motor responses consistent with, or in opposition to, pre‐potent emotional actions (i.e., approach vs. avoidance). An analogous non‐emotional task was also used to examine cue‐conflict impairment more generally. The groups demonstrated statistically equivalent performance decrements on incongruent versus congruent trials on both tasks. However, within the schizophrenia group, the incongruency effect was significantly greater in the emotional versus non‐emotional task. These data suggest that, while patients with schizophrenia were able to employ contextual response cues to override competing emotional responses, they were slower to resolve emotional versus non‐emotional response conflict. When patients were subdivided according to the presence or absence of disorganized symptoms, this effect was confined to patients with disorganized symptoms.     

Motor creativity: the roles of attention breadth and working memory in a divergent doing task

We evaluated the dual-pathway model to creativity in a motor context. The model describes separate flexibility and persistence pathways that are affected differently by breadth of attention and working memory. Motor creativity was tested using a divergent doing task. In Experiment 1 participants performed the divergent doing task after attention was broadened, narrowed or not manipulated. In Experiment 2, the divergent doing task was performed with a low or high working memory load. We found that a broad attention increased flexibility but not persistence. Also originality was unaffected. Taxing working memory did not affect persistence, flexibility or originality. The results provide partial support for the dual-pathway model in motor creativity. Discusion focusses on increased demands for the appropriatness of a solution in divergent doing relative to divergent thinking and to degree to which this implies a more general shortcoming of the dual-pathway model.     

Exploring Correlates of Alcohol-Specific Social Reactions in Alcohol-Involved Sexual Assaults

This exploratory study examined demographic, assault, and disclosure factors as predictors of survivors’ decisions to disclose preassault alcohol use and social reactions to their preassault alcohol use. Of survivors drinking prior to assault, those with more education and greater alcohol impairment or resistance during assault were more likely to disclose preassault drinking. Of women disclosing preassault drinking, those with more education and more violent assaults received more negative social reactions specific to their preassault drinking. Such negative reactions were more common for those telling parents, police, or medical professionals. Women with less education received more positive and negative social reactions specific to their preassault drinking. Disclosing preassault drinking in greater detail was related to positive social reactions specific to preassault drinking and greater alcohol impairment during assault was associated with both positive and negative social reactions specific to preassault drinking. Implications for research and intervention are provided for survivors disclosing alcohol-related sexual assaults.     

Working memory and fine motor skills predict early numeracy performance of children with cerebral palsy

Early numeracy is an important precursor for arithmetic performance, academic proficiency, and work success. Besides their apparent motor difficulties, children with cerebral palsy (CP) often show additional cognitive disturbances. In this study, we examine whether working memory, non-verbal intelligence, linguistic skills, counting and fine motor skills are positively related to the early numeracy performance of 6-year-old children with CP. A total of 56 children (M = 6.0, SD = 0.61, 37 boys) from Dutch special education schools participated in this cross-sectional study. Of the total group, 81% of the children have the spastic type of CP (33% unilateral and 66% bilateral), 9% have been diagnosed as having diskinetic CP, 8% have been diagnosed as having spastic and diskinetic CP and 2% have been diagnosed as having a combination of diskinetic and atactic CP. The children completed standardized tests assessing early numeracy performance, working memory, non-verbal intelligence, sentence understanding and fine motor skills. In addition, an experimental task was administered to examine their basic counting performance. Structural equation modeling showed that working memory and fine motor skills were significantly related to the early numeracy performance of the children (β = .79 and p < .001, β = .41 and p < .001, respectively). Furthermore, counting was a mediating variable between working memory and early numeracy (β = .57, p < .001). Together, these findings highlight the importance of working memory for early numeracy performance in children with CP and they warrant further research into the efficacy of intervention programs aimed at working memory training.     

The coupling of head,reach and grasp movement in nine months old infant prehension

In 9-month-old-infants adjustments in the reaching pattern to sudden changes in object location were examined. An attractive ball was presented to the infants at their midline and on some trials (perturbation trials) the ball suddenly changed position 15 cm to the right or left during the reach. For the perturbed trials the movement times approximately doubled compared to the control trials and significantly fewer balls were grasped. The results indicate that infants need to finish the first movement before being able to redirect the reach to a new destination. The correlation between the latency of the head and hand adjustment to the perturbation were 0.85 and 0.78 for movements to the left and to the right, respectively, indicating a tight coupling. The time between the start of the perturbation and peak velocity (TPPV) was significantly shorter for the head movement than for the hand movement, indicating that the head is leading the hand.     

Motor Imitation in Young Children with Autism: What's the Object?

Two studies investigated the nature of motor imitation in young children with autism. Study 1 compared different types of motor imitation in 18 autistic children, 18 children with developmental delay, and 18 normally developing children. Results revealed weaker imitation skills for the autistic group, though all groups demonstrated a similar pattern of performance across different imitation domains. Imitation of body movements was more difficult than imitation of actions with objects, and imitation of nonmeaningful actions was more difficult than imitation of meaningful actions. Study 2 investigated concurrent and predictive relations between imitation and other developmental skills within a sample of 26 two-year-old children with autism. Results suggested that imitation of body movements and imitation of actions with objects represent independent dimensions. Imitation of body movements was concurrently and predictively associated with expressive language skills, and imitation of actions with objects was concurrently associated with play skills. Improvements in both motor imitation domains occurred over a 1-year period.     

On the Origins of Children's Compliance and Opposition: Family Context, Reinforcement, and Rules

Interactional synchrony and context dependent reinforcement are presented as similar phenomena in this discussion of children's dispositions to comply with or to oppose parental instructions. I argue that consistent and appropriate parental reactions to the full range of a child's response repertoire will establish a family context conducive to positive reinforcement of child compliance. In contrast, inconsistent parental reactions appear to create a chaotic family context conducive to the negative reinforcement of child opposition. Depending on these two forms of context, the parents and children seem to generate distinctive personal rules which outline the functional arrangements of context, behavior and reinforcement. The importance of these personal rules in helping parents and children to improve the lawfulness of family context is highlighted.